When I returned to the covert narcissist after one month of no contact, he escalated all his manipulations to the extreme levels such as plenty of triangulation. Why can he be attacking me this much?

He can be attacking you this much, because you are a willing participant. Stop being a willing participant and he will need to go elsewhere…

What is the best way to learn about reincarnation on a more personal level? How do I learn about my own past lives and how they affect me?

The best way to learn about reincarnation is reading the many excellent first-person or therapist written books or engage with a certified past life regression…